High-fat dietís impact on brain explored

By Bill Snyder January 2010

Photo by istockphoto.com

Does fast food mess with your brain?

That’s one of the questions Vanderbilt scientists Kevin Niswender, M.D., Ph.D., and Aurelio Galli, Ph.D., hope to answer with the help of a $5.2 million “transformative” research grant from the National Institutes of Health (NIH).

Their hypothesis: consumption of high-fat, high-sugar foods can disrupt insulin signaling in the brain, and its regulation of neurotransmitters involved in mood and behavior. This may explain “food addiction,” and could lead to new ways to treat obesity and diabetes.

“It’s really very strange to be using this sort of addiction language for a metabolic disorder like obesity, but the basic mechanisms seem to fit,” said Niswender, assistant professor of Medicine.

In 2007, Galli and colleagues at Vanderbilt and the University of Texas in San Antonio reported that insulin, the hormone that governs glucose metabolism in the body, also regulates the brain’s supply of dopamine.

They were among the first to find a link between decreased insulin signaling, which occurs in insulin-deficient (or Type I) diabetes, and altered dopamine signaling, which contributes to addiction, schizophrenia and attention-deficit hyperactivity disorder (ADHD), and which can cause cognitive problems.

Previously Niswender and colleagues identified the signaling mechanisms by which hormones like insulin and leptin regulate feeding.

In work done at Vanderbilt, his group has uncovered mechanisms by which high-fat diets contribute to brain insulin resistance, where insulin is present, but does not work effectively.

Galli and Niswender collaborated to ask the question: could consumption of “fast foods” and soft drinks sweetened by fructose disrupt insulin signaling in the brain in a way that leads to food addiction and obesity?

Because insulin resistance impairs the normal dopamine “reward pathway,” you may have to eat “more of the same high-fat, high-carbohydrate types of foods to give you the same amount of reward you used to get,” Niswender said.